The Sansha Ship Course Research Institute for Coral Protection used a variety of equipment, including underwater robots and sonar scanners, to determine the sinkhole’s size: 300.89 meters in depth, 130 meters in width (426 feet) at the entrance, and 36 meters in width (118 feet) at the bottom. The depth of the mysterious sinkhole far exceeds the Dean’s 202-meter-deep Blue Hole in the Bahamas, which previously held the title as the world’s deepest sinkhole. The dimensions were measured during...